1. Field of the Invention
The invention relates to a solenoid valve useful, for example, in hydraulic brake systems.
2. Description of the Prior Art
In brake systems, conventional solenoid valves that are open when without current serve the function, when the brakes are in the non-actuated state, of permitting small quantities of fluid to pass through in the event of a pressure increase generated either by driver command or by a precharged fluid reservoir and, when the brakes are in the actuated state, perform the function of closing off and maintaining the pressure after a pressure increase on the actuator is completed. For large production numbers, seat valves are generally used, which can be manufactured inexpensively.
FIG. 1 shows a known solenoid valve 1 with an integrated check valve 10, for example, in particular for a hydraulic unit that is used, for example, in an antilock brake system (ABS), a traction control system (TCS), or an electronic stability program system (ESP). As is clear from FIG. 1, the conventional solenoid valve 1 has a magnet unit 2 for generating a magnetic flux that includes a housing casing 2.1 and an electric coil that is composed of a coil winding 2.3 wound onto a winding support 2.2 and can be controlled via electrical connections, and a valve cartridge 3 that includes a capsule 4, a valve insert 5, a return spring 8, and an armature 6, which is connected to a scaling pin 7 that has a sealing region 7.1 and is guided in a longitudinally mobile fashion inside the valve insert 5. The magnet unit 2 generates a magnetic force that moves the longitudinally mobile armature 6 with the sealing pin 7 toward the valve insert 5 counter to the force of the return spring 8. A magnetic flux, which is generated by the magnet unit 2 through the supply of current to the coil winding 2.3 and introduced via a cover disk, is conveyed by the valve insert 5 axially toward the armature 6 via an air gap; the supply of current to the coil winding 2.3 via the electrical connections is executed by an end stage, not shown, that is situated outside the solenoid valve 1. The valve insert 5 also accommodates a valve body 9 with a relatively small through bore that includes a valve seat 9.1 into which the sealing region 7.1, which is embodied as a sealing dome, is inserted in a sealing fashion in order to perform the sealing function of the solenoid valve 1 and to adjust a volumetric flow between the valve inlet 11 and the valve outlet 12. Consequently, once actuated, i.e. after current has been supplied to the magnet coil, a magnetic circuit is produced, which generates a closing force that acts on the armature 6 and presses the sealing region 7.1 of the sealing pin 7 into the sealing seat 9.1 of the valve body 9.